姚江-宁波平原中全新世海侵事件及古人类活动的快速响应

姚江-宁波平原是新石器河姆渡文化核心分布区,大量考古与古环境研究成果为深入探讨本地区7000年来的人地关系,尤其是新石器遗址文化间歇事件的原因创造了有利条件。本文通过对鱼山遗址地层记录的详细研究以及与区域多个遗址地层的空间对比,并对照该区自河姆渡文化一期以来古人类遗址的时空迁移过程,总结新石器文化演进中的海侵事件,并分析其与文化间歇的内在联系,初步认识如下:1)鱼山遗址从山麓到平原,地层记录存在明显差别,因此需要在不同的古地理位置获取剖面进行对比,才能重建更完整的古环境演变过程。2)鱼山遗址记录了2次海水入侵事件,分别发生于6300~6000cal.aB.P.和4500~3400cal.aB.P.,这两次事件与区内其他遗址文化层堆积中普遍叠压的自然淤积层或文化层缺失现象具有良好对应关系;研究区另有部分遗址在5400~5300cal.aB.P.也存在海水入侵迹象。3)新石器遗址时空分布呈现阶段性变化,河姆渡文化一、二期,遗址数量少,增幅小,主要分布于山麓缓坡地带,反映海水入侵造成研究区土地资源的局限性。河姆渡文化三、四期的遗址数量显著增加,且向开阔平原地带扩散,表明较稳定的海平面使研究区平原成陆面积增大,古人类对海岸带的利用快速扩张。良渚末期,遗址大幅度减少,直至商周才重新增多,反映持续的海水入侵制约古人类活动强度。上述遗址时空迁移特征反映海岸带古人类活动对环境变化的快速响应。

MIDDLE HOLOCENE SEAWATER INTRUSION AND HUMANA RAPID RESPONSE IN THE YAOJIANG-NINGBO COASTAL PLAIN,CHINA

Yaojiang-Ningbo coastal plain (29°35'~30°10'N,120°55'~121°58'E) is the core distribution area of Neolithic Hemudu culture. A large number of previous archaeological and paleoenvironmental researches are favorable for exploring the human-environment relationship over the past 7000 years, especially the causes of Neolithic cultural interruptions in this region. In this paper, we carried out the detailed studies on the stratigraphic records of a profile ca. 172 cm deep obtained from the Neolithic Yushan site (30°02'N,121°33'E) and a spatial comparison of stratigraphic records in the region. Combined with the spatial and temporal migrations of ancient human settlements during the period from the first phase of Neolithic Hemudu culture to Shang and Zhou dynasties, we summarized the marine intrusion events and analyzed its linkage to the cultural interruptions in the evolution of Neolithic cultures in the Yaojiang-Ningbo coastal plain. The preliminary results are as follows. First, there are obvious variations in the stratigraphic records preserved in different profiles, which are distributed at the foothill and open plain at the Yushan site. It is thus necessary to compare profiles derived from different paleogeographic positions to obtain more informative paleoenvironmental evolution processes. Secondly, the Neolithic Yushan site has recorded two major seawater intrusion events, which occurred during 6300~6000 cal.a B. P. and 4500~3400 cal.a B. P., respectively. These two events had a good correspondence with the natural sedimentation layers formed between cultural layers or the absence of cultural layers at many Neolithic sites in the region. In addition, some other sites in the study area also show signs of seawater intrusion at 5400~5300 cal.a B. P. Thirdly, the spatial and temporal distributions of ancient human settlements changed at several stages. During the first and second phases of Hemudu culture, the number of sites was small and increased little, and the sites mainly distributed at the foothills, reflecting the limitations of land resources caused by seawater intrusion. The number of sites increased significantly and the sites spread to the open plain in the third and fourth phases of Hemudu culture, indicating the expansion of new lands and associated rapid human colonization due to the relatively stable sea level at this stage. At the terminal stage of Liangzhu culture, the number of sites reduced greatly and recovery didn't occurred until the Shang and Zhou dynasties, reflecting that the long-lasting environmental deterioration induced by seawater intrusion restricted the intensity of human activities at that time. The spatiotemporal migration pattern of the sites mentioned above reflected the rapid response of the ancient human societies to the coastal environmental change.